The present invention relates to a pickup cartridge and a pickup cartridge mounting device therefor for facilitating replacement of the pickup cartridge alone.
A conventional tone arm is pipe-shaped and has an electric connector for connecting the pickup cartridge to a circular recess at its front end. Therefore, for mounting a replaceable pickup cartridge to the front end of the tone arm, the pickup cartridge is made replaceable by forming it integrally with a head shell having a plug at its rear end, this plug to be inserted in the circular recess of the front end of the tone arm and to be electrically connected to the inner electric connector. Then the pickup cartridge is mounted by clamping an annular lock nut at the tone arm front end.
As far as the replaceable cartridge itself is concerned, if the pickup cartridge portion and the head shell portion are formed integrally with each other as mentioned above, replacement of the pickup cartridge can be costly since the head shell must also be replaced. In view of this, it is a general practice, at present, to detachably mount the pickup cartridge to the head shell, and to integrally form the head shell to the tone arm front end in advance, or to detachably mount it to the tone arm front end using the above-mentioned lock nut. Thus, the head shell itself is used as an accessory. The pickup cartridge is generally mounted to the head shell in such a manner that it is detachably attached to the undersurface of the head shell by being clamped by two mounting screws from the top surface of the plate-shaped head shell. However, such a structure is disadvantageous in that the mounting of the cartridge to the head shell is not dependable, since the mounting condition varies with the clamping tightness of the two mounting screws. It is also difficult to correctly ascertain the verticality of the stylus tip of the pickup cartridge. Although the two mounting screws are clamped symmetrically about the central axis of the pickup cartridge, their clamping positions will be laterally shifted at both sides of the central axis if their degrees of clamping tightness to the head shell are different. Thus, such a structure is disadvantageous in that jolting may be caused which results in the generation of abnormal resonance, or the stylus may be off the central axis and lose its verticality.